最近写了一个简单的聊天室应用，可以发送表情，更改头像这些功能。主要技术点就是怎样把表情图片放到textview等Ui控件中展示。这里废话不多说，下面是效果图：

 这里主要讲下怎样把文本替换到表情，先说下思路，首先我们的图片是保存在本地资源目录drawable中而所有的资源文件都是R这个类来管理，所以我们可以利用正则表达式找出图片id包装成ImageSpan然后把ImageSpan放到SpannableString中，最后把SpannableString放入edittext中，下面是源码：

package com.coreandroid.util; 
 
import java.lang.reflect.Field; 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 
 
import android.content.Context; 
import android.text.Spannable; 
import android.text.SpannableString; 
import android.text.style.ImageSpan; 
import android.util.Log; 
 
import com.coreandroid.chart.R; 
 
public class ExpressionUtil { 
  /** 
   * 对spanableString进行正则判断，如果符合要求，则以表情图片代替 
   * 
   * @param context 
   * @param spannableString 
   * @param patten 
   * @param start 
   */ 
  public static void matchExpression(Context context, 
      SpannableString spannableString, Pattern patten, int start) 
      throws Exception { 
    Matcher matcher = patten.matcher(spannableString); 
    while (matcher.find()) { 
      String key = matcher.group(); 
      if (matcher.start() < start) { 
        continue; 
      } 
      Field field = R.drawable.class.getDeclaredField(key); 
      int resId = field.getInt(null); // 通过上面匹配得到的字符串来生成图片资源id 
      if (resId != 0) { 
        ImageSpan imageSpan = new ImageSpan(context, resId); // 通过图片资源id来得到bitmap，用一个ImageSpan来包装 
        int end = matcher.start() + key.length(); // 计算该图片名字的长度，也就是要替换的字符串的长度 
        spannableString.setSpan(imageSpan, matcher.start(), end, 
            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); // 将该图片替换字符串中规定的位置中 
        if (end < spannableString.length()) { // 如果整个字符串还未验证完，则继续。。 
          matchExpression(context, spannableString, patten, end); 
        } 
        break; 
      } 
    } 
  } 
 
  /** 
   * 得到一个SpanableString对象，通过传入的字符串,并进行正则判断 
   * 
   * @param context 
   * @param str 
   * @return SpannableString 
   */ 
  public static SpannableString getExpressionString(Context context, 
      String str, String zhengze) { 
    SpannableString spannableString = new SpannableString(str); 
    Pattern sinaPatten = Pattern.compile(zhengze); // 通过传入的正则表达式来生成一个pattern 
    try { 
      matchExpression(context, spannableString, sinaPatten, 0); 
    } catch (Exception e) { 
      Log.e("dealExpression", e.getMessage()); 
    } 
    return spannableString; 
  } 
 
} 

下面是聊天记录列表的adapter，这里主要是动态的改变每个Item的布局来区分是自己还是他人的发言，具体源码如下：

package com.coreandroid.adapter; 
 
import java.text.DateFormat; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import java.util.List; 
 
import android.content.Context; 
import android.text.SpannableString; 
import android.text.TextUtils; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ImageView; 
import android.widget.RelativeLayout; 
import android.widget.TextView; 
 
import com.coreandroid.chart.R; 
import com.coreandroid.entity.MessageInfo; 
import com.coreandroid.util.CommonUtils; 
import com.coreandroid.util.ExpressionUtil; 
 
public class ChartListAdapter extends BaseAdapter { 
 
  private Context context; 
 
  private LayoutInflater inflater; 
 
  private List<MessageInfo> data; 
 
  private DateFormat df; 
 
  public ChartListAdapter(Context context, List<MessageInfo> data) { 
    super(); 
    this.context = context; 
    inflater = LayoutInflater.from(context); 
    this.data = data; 
    df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
  } 
 
  @Override 
  public int getCount() { 
    return data.size(); 
  } 
 
  @Override 
  public Object getItem(int position) { 
    return data.get(position); 
  } 
 
  @Override 
  public long getItemId(int position) { 
    return position; 
  } 
 
  @Override 
  public View getView(int position, View convertView, ViewGroup parent) { 
    ViewHolder holder = null; 
    if (convertView == null) { 
      convertView = inflater.inflate(R.layout.chart_list_item, null); 
      holder = new ViewHolder(convertView); 
      convertView.setTag(holder); 
    } else { 
      holder = (ViewHolder) convertView.getTag(); 
    } 
    holder.setData((MessageInfo) getItem(position)); 
    return convertView; 
  } 
 
  private class ViewHolder { 
    private ImageView image; 
    private TextView text; 
    private TextView title; 
    private RelativeLayout rl; 
 
    public ViewHolder(View convertView) { 
      image = (ImageView) convertView 
          .findViewById(R.id.chart_list_item_headicon); 
      text = (TextView) convertView 
          .findViewById(R.id.chart_list_item_message); 
      title = (TextView) convertView 
          .findViewById(R.id.chart_list_item_title); 
      rl = (RelativeLayout) convertView 
          .findViewById(R.id.rl_chart_list_bottom); 
    } 
 
    public void setData(MessageInfo msg) { 
      RelativeLayout.LayoutParams rl_tv_msg_left = (RelativeLayout.LayoutParams) text 
          .getLayoutParams(); 
      RelativeLayout.LayoutParams rl_iv_headicon_left = (RelativeLayout.LayoutParams) image 
          .getLayoutParams(); 
      RelativeLayout.LayoutParams rl_tv_title = (RelativeLayout.LayoutParams) title 
          .getLayoutParams(); 
      RelativeLayout.LayoutParams rl_buttom = (RelativeLayout.LayoutParams) rl 
          .getLayoutParams(); 
      if (!CommonUtils.getDeviceId().equalsIgnoreCase(msg.getUsermac())) { 
        // 根据本地的mac地址来判断该条信息是属于本人所说还是对方所说 
        // 如果是自己说的，则显示在右边；如果是对方所说，则显示在左边 
        rl_buttom.addRule(RelativeLayout.ALIGN_PARENT_TOP); 
 
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_LEFT); 
        rl_tv_title.addRule(RelativeLayout.BELOW, 
            R.id.rl_chart_list_bottom); 
 
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_LEFT); 
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 
        rl_tv_msg_left.addRule(RelativeLayout.RIGHT_OF, 
            R.id.chart_list_item_headicon); 
        text.setBackgroundResource(R.drawable.incoming); 
        String titleStr = msg.getUsermac() + "-" 
            + df.format(new Date()); 
        title.setText(titleStr); 
      } else { 
        rl_buttom.addRule(RelativeLayout.ALIGN_PARENT_TOP); 
 
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); 
        rl_tv_title.addRule(RelativeLayout.BELOW, 
            R.id.rl_chart_list_bottom); 
 
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_RIGHT); 
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM); 
        rl_tv_msg_left.addRule(RelativeLayout.LEFT_OF, 
            R.id.chart_list_item_headicon); 
        text.setBackgroundResource(R.drawable.outgoing); 
        String titleStr = df.format(new Date()) + "-" 
            + msg.getUsermac(); 
        title.setText(titleStr); 
      } 
      if (!TextUtils.isEmpty(msg.getHeadImage())) { 
        image.setImageBitmap(CommonUtils.strConvertBitmap(msg 
            .getHeadImage())); // 设置头像 
      } else { 
        image.setImageResource(R.drawable.im); 
      } 
      String str = msg.getMessage(); // 消息具体内容 
      try { 
        SpannableString spannableString = ExpressionUtil 
            .getExpressionString(context, str, CommonUtils.PATTERN); 
        text.setText(spannableString); 
      } catch (Exception e) { 
        e.printStackTrace(); 
      } 
    } 
  } 
 
} 

源码下载：Android聊天室应用

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